The present invention relates to a fuel cell system which is, for example, preferably used as an auxiliary power source of an automotive vehicle.
Automotive vehicles are recently equipped with many electronic devices. Accordingly, a great amount of electric power is required for the automotive vehicle. In general, the automotive vehicle installs an alternator to generate electric power and a battery to store electric power. Meanwhile, various kinds of fuel cells are already proposed as effective devices capable of supplying electric power to the automotive vehicles.
One of the conventionally known fuel cells is a polyelectrolyte fuel cell (hereinafter, referred to as PEFC). Furthermore, as a fuel cell system using this fuel cell, the Japanese Patent Application Laid-open No. 2003-184666, corresponding to the U.S. Patent Application Publication No. U.S. 2003/0168024A1, discloses a system which uses gasoline or methanol as the fuel and generates electric power by using hydrogen extracted from this fuel through a reformer.
However, according to such a fuel cell system, it is necessary to install a heavy and expensive reformer on a vehicle. Furthermore, the reformer is generally dissatisfactory in its performance because it cannot quickly and accurately respond to frequent accelerating/decelerating and stopping operations or other load changes occurring in the automotive vehicle.
On the other hand, another example of the fuel cell is a direct methanol fuel cell (hereinafter, referred to as DMFC) which is for example disclosed in “A Guide to Visual Technology—Everything in Fuel Cell—,” first edition, pp 209 to 219, written by Konosuke IKEDA, published by Nippon Jitsugyo Publishing Co. Ltd., Aug. 20, 2001. The direct methanol fuel cell is a kind of PEFC, and is characterized in that no reforming of methanol into hydrogen is required and accordingly the methanol can be directly used as the fuel to generate electric power. Accordingly, the fuel cell system using the DMFC requires no reformer.
In view of the foregoing, it is useful to utilize a fuel cell system incorporating the DMFC or a comparable fuel cell capable of generating electric power with methanol or other directly supplied fuel, as an auxiliary power source of an automotive vehicle to supply electric power.
However, the fuel cell system incorporating the DMFC requires an additional container to be installed in an automotive vehicle for storing methanol or comparable fuel. Securing a sufficient space for this container is not easy because an available space in an automotive vehicle is limited.